1. Field of the Invention
The present invention is directed to rope chain jewelry made of a precious metal. More precisely, the present invention is directed to unique wire links interlaced together to form a rope chain.
2. Description of the Prior Art and Related Information
Jewelry rope chains have been for decades been made by hand. The basic construction element used to assemble a rope chain was an annular link cut from a solid wire stock. The wire stock was preferably made of a precious metal such as 14 karat gold.
FIG. 1 shows such a prior art link 1 which has a gap g, with an inner circumferential chord distance B. In conventional rope chains, the inner circumferential chord B of the gap g in each link is slightly larger than the cross section of the link 1 so that one link can pass through the gap of another link. By assembling one link to another, an entire rope chain can be built in this manner. Indeed, a rope chain having the appearance of a double helix is commonly built in this fashion.
It is clear that this is a labor intensive process, but, with good workmanship, the final product is typically very attractive. There have been efforts to automate the process, but the quality of a machine-made rope chain is lower than a hand-made rope chain.
To make the link, a wire formed from a precious metal having a circular cross section is wound around a mandrel to give the wire a coiled shape. The coil is next cut at eccentric angles so that the respective gaps of each link are staggered. The thickness of the cutting disk somewhat determines the gap size.
Because the cut links still retain their coiled shape, the ends of the link are not co-planar. Thus, each link is accordingly pressed between pressure rollers to flatten the link thereby cold working the entire link so that it lies within a single plane. The flattening pressure creates opposed flat surfaces on diametrically opposed sides of the link. The flattening pressure also bends the link so that the flat faces are parallel to the plane defined by the circumference of the link. Also, after flattening, the ends of the link forming the gap lie in the same plane.
Conventional rope chains were made from split annular rings having approximately a 3:1 ratio of inner diameter to the major wire dimension. U.S. Pat. No. 4,651,517 to Benhamou disclosed that it was possible to substantially reduce the amount of precious metal required to produce a rope chain of equivalent dimension by using a thinner wire annular ring and changing the ratio of ring inner diameter to major wire dimension to just over X times greater than the major wire dimension, wherein X is an odd number greater than 3. Thus, by having the ratio of ring inner diameter to major wire dimension of approximately 5:1, 7:1, etc., it was possible to obtain rope chains of similar diameter and length as the 3:1 ratio rope chain, but with a significant reduction of precious metal weight used in the chain.
U.S. Pat. No. 4,996,835 to Rozenwasser disclosed that further weight savings can be achieved in producing a rope chain by using non-circular, elongated shaped rings having a major axis defining longer outer and inner diameters, and a minor axis defining shorter outer and inner diameters, wherein the gap was oriented in a link section parallel to the major axis and the shorter inner diameter was just over X times greater than the cross-section of the link wire. Variable X was a number equal to or greater than 2, and the links were positioned in the chain so that the longer outer diameter defined the width of the chain.
U.S. Pat. No. 5,185,995 to Dal Monte disclosed a jewelry rope chain having link members having an outer peripheral volume and an inner peripheral volume, the boundary between said outer and inner peripheral volumes being defined by a phantom bisecting surface drawn midway between an outermost perimeter and an innermost perimeter of each link member, wherein the link wire had a majority of its weight lying within said outer peripheral volume of said link member and a balance of its weight lying within said inner peripheral volume of said link member. Dal Monte thus disclosed a jewelry rope chain having reduced the amount of precious metal without increasing the number of links needed to assembly the rope chain of a given width, or outside diameter, and length by modifying only the shape of the cross-section of the wire used to form the individual links.
U.S. Pat. No. 5,361,575 to Rozenwasser disclosed a jewelry rope chain comprised of a plurality of links wherein each link featured a wire cross-section including a major axis defining a longer dimension and a minor axis defining a shorter dimension, said longer dimension being in the plane of the link and the shorter dimension being perpendicular thereto, the ratio of said longer dimension to said shorter dimension being greater than 1.3:1 but less than 3:1. Further, the gap of each chain link was narrower than the longer dimension of the wire cross-section of the link.
In view of the foregoing, there is still a need for reducing the quantity of precious metal without increasing the number of links required to assemble an entire rope chain of a given a outside diameter and rope chain length. Further, the appearance of the rope chain should be smooth, tight, and non-corrugated to be attractive to the consumer.